1. Field of the Invention
The present invention relates to a sterilization tray and a moist heat sterilization method, and more particularly, the invention relates to a moist heat sterilization method for sterilizing a resin container filled with a medicine, food or the like using steam or hot water, and to a sterilization tray used for this method.
2. Description of the Related Art
In a case in which a resin container 1 such as an infusion solution bag as illustrated in FIG. 12 is subjected to moist heat sterilization, the resin container 1 is placed on a sterilization tray 2 and is put into a high pressure steam sterilization apparatus such as an autoclave, or a hot water spray type sterilization apparatus. Thus, the resin container 1 and the infusion fluid or the like inside the resin container are sterilized together by means of high pressure steam or hot water.
The resin container 1 illustrated in FIG. 12 is a multi-chamber container (double bag) in which a filled part 1a filled with an infusion solution and an empty chamber part 1b are divided by a partition part 1c, and after a sterilization treatment, the empty chamber part 1b is filled with a drug (a powder, a liquid or the like) and a gas barrier film may be attached thereto in order to protect the performance of the drug. Meanwhile, the multi-chamber container is not limited to a two-chamber container, and a three-chamber container and a four-chamber container are also available. Also, the sheet for the protection of performance is not limited to a gas barrier film, and an aluminum sheet, other sheets for making chambers for enclosing a desiccant or an oxygen scavenger, and the like are also available.
The bottom of the sterilization tray 2 is composed of a perforated plate (perforated metal) so that sterilization of the resin container 1 by means of high pressure steam or hot water, and dehydration and drying after sterilization can be facilitated. Meanwhile, a stopper part 1d of the resin container 1 is supported by a support 2a fixed to the bottom of the sterilization tray 2.
When moist heat sterilization is carried out in a state in which such a resin container 1 is placed on the sterilization tray 2, the resin container 1 is deformed as illustrated in FIGS. 13A and 13B, and there is a problem that creases are generated particularly in the peripheral edge of the resin container 1, or traces of the openings of the perforated plate (sterilization traces) 1e are produced.
When creases are generated in the peripheral edge or the like of the resin container 1, the attachment of the gas barrier film in the subsequent process is adversely affected. Furthermore, the sterilization traces 1e cause diffuse reflection of light at the time of performing an inspection if any foreign materials are present inside the resin container 1, and make it difficult to find foreign materials in the inside. Also, there is a problem that the sterilization traces 1e make characters, symbols and the like printed on the surface of the resin container 1 poorly visible.
There have been hitherto suggested the inventions described in JP 1992-176465A (JP-H04-176465A), JP 1993-253276A (JP-H05-253276A), JP 1998-33643A (JP-H10-33643A) and JP 1993-76297U (JP-H05-76297U) as sterilization trays that prevent deformation of this kind of resin containers.
In the invention described in JP 1992-176465A (JP-H04-176465A), buoyancy is imparted to the resin container by filling the inside of a water tank type tray with hot water, and thus the container itself being deformed under the weight of the content is prevented.
In the invention described in JP 1993-253276A (JP-H05-253276A), in order to prevent the resin container that has been subjected to a high pressure steam sterilization treatment from being deformed into a so-called semicylindrical shape (the bottom being flat-shaped, and the upper part being curved), the shape of the bottom face of the sterilization tray is made into the shape of the resin container, and thereby, the resin container is prevented from being deformed into a semicylindrical shape.
The invention described in JP 1998-33643A (JP-H10-33643A) is a swinging rotation type spray style retort sterilization method, in which when a product inside a pouch is heat sterilized by spraying and spouting steam or the like, the pouch is restrained to the tray by clamping the edge ear parts of the pouch with a pouch gripping member such as a clip mechanism or a bolt, and thus the movement of the pouch at the time of subjecting the tray to swinging rotation is prevented, or the occurrence of creases, pinholes and the like in the pouch is prevented.
In the invention described in JP 1993-76297U (JP-H05-76297U), in order to prevent curling or deformation occurring in the ear parts of a vacuum pack (material to be treated) of food as a result of a heating treatment, plural partitioning crosspieces are provided inside the tray by leaving an interval to the extent that the ear parts of both edges of the material to be treated can be placed, and a heating treatment is carried out such that when trays are superposed, the ear parts of the material to be treated are clamped between the upper part of the partitioning crosspieces and the bottom plate of a tray.